Spark-plug.



C. H. DUFFY.

SPARK PLUG.

APPLICATION FILED APR. 16. I918.

Patented Apr. 29, 1919.

awuewbo'z M JNRIS PETERS cm. PHOYO umo K'Asnmc UNITED STATES PATENT onnron,

CHARLES HUGH DUFFY, OF CHEVY CHASE, MARYLAND.

SPARK-PLUG.

Specification of Letters Patent.

Patented Apr. 29, 1919.

Application filed April 16, 1918. Serial No. 228,935.

- make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

This invention relates to spark-plugs for internal combustion engines, and has for its object to provide improvements in the method of and construction for seating a slightly tapered insulating core within a complementally slightly tapered spark-plug shell.

The term slightly tapered appearing in this specification has reference to a taper which produces or provides what is known as a stlcking taper, the same being a taper which sticks or seizes when placed within a complemental taper even to such an extent that no further or additional holding or retaining means or medium is necessary to hold the tapered members in close or tight engagement both against asual displacement or relative rotation.

In that type of spark-plugs, as for example that disclosed in U. S. patent to Davis & Mellen, No. 690,640 patented Jan. 7th, 1902, in which a slightly tapered insulating core is seated in a complementally tapered shell, a perfectly gas tight joint or union can only be obtained by grinding or lapping the complemental tapers of the core and shell.

This invention has for its object to provide a metal band over the slightly tapered portion of the insulating core, and between the core and the complementally tapered portion of the shell; said metal band being preferably formed on and integral with the core-retaining gland.

The invention consists in the'arrangement of the parts and in the method of spinning a metal band around the insulating core and between the complementally tapered portion thereof and the shell, in such manner that a close conformation between the parts is assured, and a consequent as-tight joint is effected, as will be first fully described and afterward specifically pointed out in the appended claims.

Referring to the accompanying drawing:

Figure 1, is a vertical sectional view, of a spark-plug constructed in accordance with this invention, shown in elevation.

Fig. 2, is a similar view, .inverted, illustrating the manner of assembling'the parts.

Fig. 3, is an elevation of the gland, insulaand central electrode after being assem- Fig. 4, is an elevation of the gland before being assembled in the shell, and Fig. 5, is a vertical sectional view showing the gland, shell, insulation and central electrode in an assembled position.

Like numerals of reference indicate the same parts throughout the several figures in which:

1, indicates a sparl plug constructed in accordance with this invention. 2, indicates the insulating'core, 3 the shell and 4, the thimble-gland. The core 2, is provided with a shoulder 5, a central enlarged portion 6, a slightly tapered portion 7, and a reduced lower portion 8. 9 indicates the central electrode, the sparking end 10 of which, in the type shown in the drawing, is of disk formation, the periphery of which is spaced away from the shell 3, to form an annular spark-gap 11. v

The shell 3 is internally threaded at 12, and externally threaded at 13, for connection with a motor. Within the shell 3, and

the insulating core being b low the threaded portion 12, isa slightly tapered portion 14 complemental to the slightly tapered portion 7 of the core 2.

The gland 4 is bored to receive the core 2,

and includes a threaded portion 15, having an internal annular shoulder 16, and a thin depending tubular portion 17, which encompasses the slightly tapered portion 7 of the core 2, when the said core is initially inserted within the gland 4;

Having thus fully described the several parts of the spark-plug, the method of assembling the parts is as follows:

-Theassembly is facilitated by inverting the parts, as shown in Fig. 2. The core 2, is inserted in the gland 4, and the shell 3, is placed on the gland, and threaded thereon by rotation, so as to progress the shell 3 with relation to the gland 4. The end of the tubular portion 17 of the gland 4, enters the slightly tapered portion 14 of the shell i 3, engaging the beginning of the tapered annular wall ofrsaid slightly tapered portion.

-As the shell 3, is rotated down on the gland 4, the slightly tapered portion 14 of the shell 3, gradually spins the tubular portion 17 of the gland 4, inwardly and around the complementally tapered portion of the core 2, and at the same time, said tubular'portion 17 is caused to conform closely to the tapered portion 14 of the shell 3, so that whenthe tapered portion 7 of the core 2 reaches its limit of progress within the tapered portion 14 of the shell 3, the spun portion 17 has formed a closely conforming band around the said tapered portion 7 of the core 2, and between said tapered portion 7, and the complementally tapered portion 14 of the shell 3.

It will be understood that during this spinning operation, the core 2, is being rotated by and with the gland 4, so that there is no relative rotation between the core 2, and the tubular portion 17 which is being spun on and around the tapered portion 7 of the core 2; consequently the spun portion or band 17 grips the tapered portion 7 of the core in a manner which is most effective 'to produce a gas-tight union between the stood that in spinning and disposing the metal band 17 between the complemental tapers 14 and 7, a sticking action is eifected between the taper 7 and the band 17 and between the band 17 and the taper 14, in such manner that an air-tight union or joint between these elements does not depend wholly upon the pressure maintained by the threaded portion 15 of the gland 4. In this instance the principal function of the threaded connection between the gland 4 and shell 3 is to rotate the band portion 17 and insulating core with relation to the shell 3, and to spin the band portion between the "complemental tapers 7 and 14 and to progress the band portion '17 and taper 7 into the complemental taper 14 until a sticking action is efiected. This function is accomplished by relatively slightpressure of the gland 4 longitudinally of the insulating core, while after the complemental tapers are positioned, the sticking character of the tapers 7 and 14 relieves the threads of thegland 4 from holding the insulating core' against the full explosive force in the motor.

Asa matter of fact the insulating core is effectively held in position by a transverse gripping of the complemental tapers rather than by pressure applied longitudinally of the insulating core in the direction of the shell.

' By means of this construction and method, a perfectly tight seating of the core is effected, while the core 2, and gland 4 are readily demountable from the shell 3, as a unit, and upon reassembly, the initial conformation of the parts is assured.

What I claim as new and desire to secure by Letters Patent of the United States. is:

1. A spark-plug of the type in which the insulating core and the metal shell, are pro vided with slightly tapered portions complemental to each other, an insulating core having a'sticking taper, a metal shell having 'a sticking taper complemental to the sticking taper of the insulating core, and a metal "band closely'encompassing the sticking taper v of the insulating core, said plug including means providing for rotation of said insulat ing core and metal band with relation to the shell to' progress the insulating core and metal band inwardly of the shell, said met-a1 band and closely conforming to the complemental stickingtaper in the metal shell.

. 2. A spark-plug of thety-pe in which the V insulating core and the metal shell are provided with slightly tapered portions complemental to each other, an insulating core having a sticking taper, a metal shell having a sticking taper complemental to the sticking taper of the insulating core, and a thin readily distortable metal band closely encompassing the sticking taper of the insulating core, said plug including means proand metal band with relation to the shell to inwardly of the shell, said metal band and closely conforming to the V complemental sticking taper in the metal shell.

lprogress the insulating core and metal band r 3. A spark-plug including an. insulating 3 'core provided with a sticking taper inter- "mediate its ends, a metal shell to receivethe insulating core, the shell being provided with a sticking taper complemental to the sticking taper onthe insulating core, and a metal'band rotatable with the insulating core within the shell and spun on and around i the sticking taper of the insulating core and disposed between the same and the complemental stickingtaper in the'metal shell. '4. A spark-plug including a. metal shell provided with an internal stickingv taper, a

core-retaining gland for connection with said: shell, an insulating core within said gland, the core being provided with a stickin the shell, thesaid glandbeing provided with a readily distortable tubular depending ing taper complemental to the sticking taper 105 7 viding for rotation of said insulating core portion spun on. and around the sticking taper of the insulating core to form a band thereon, and closely conforming to the stick ing taperin the shell. i

5. A spark-plug including a metal shell threaded for connection with a motor and having an internal here which includes. a sticking taper, an insulating core and a suitable electrode, a gland for connection with said shell,-a tubular portion on said gland and an internal shoulder therein, a sticking taper on said insulating core complemental to the sticking taper in the shell, said tubular portion on the gland being adapted to receive the sticking taperof the'insulating core, the said tubular portion being adapted to engage the said sticking taper in the shell to spin said tubular portion on and around the sticking taper of the insulating core and between the same and the complemental sticking taper'in the'shell. i

6. A spark-plug including a metal shell having a bore therein which includes a sticking taper, an insulating core having an enlarged central portion forming an upper shoulder and a sticking taper complemental to the sticking taper in the shell, a gland for connection with said shell and having an internal shoulder complemental to the shoulder on the insulating core and having a tubular portion to receive the sticking taper of the insulating core, said tubular portion be ing adapted to engage the sticking taper in the shell to spin the tubular portion on and around the sticking taper of the insulating core and between the same and the sticking taper in the shell complemental to the stick ing taper of the insulating core.

7. A spark-plug comprising a metal shell having a sticking taper therein, an insulating core having an enlarged portion thereon forming an upper shoulder and a sticking taper complemental to the sticking taper in the shell, a gland having a shoulder therein complemental to the shoulder on the insulating core and having a tubular portion to receive the sticking taper of the insulating core, said tubular portion being adapted to engage and rotate on the sticln'ng taper in the shell to spin said tubular portion on and around the sticking taper of the insulating core and to grind a gas-tight joint between the spun tubular portion and the sticking ta er in the shell.

8. A spark-plug including a metal shell having a sticking taper therein, a gland for connection with said shell, an insulating core to be received by said gland, a tubular portion on said gland adapted to engage the sticking taper in the shell and to rotate thereon to spin the tubular portion on and around said insulating core.

9. A spark-plu including a shell having a sticking taper t erein, an insulating core having an enlarged portion forming an uppershoulder and a lower sticking taper complemental to the sticking taper in the shell, a gland .for connection with the shell and provided with an internal shoulder complemental to the said shoulder on the insulating core and provided with a readily distortable portion, said insulating core being adapted to be received by said gland, the said readily distort-able portion on said gland being adapted to engage the sticking taper in the shell and to rotate thereon to spin the read ily distortable portion on and around the complemental sticking taper of the insulating'coreand to grind a, gas-tight joint between the sticking taper in the shell and the readily distortable portion of the gland.

10. A spark-plug including a shell, a gland, an insulating core provided with a sticking taper, a readily distortable portion on the gland, said gland 'being adapted to 'receive the insulating core, said shell being provided with means therein to be engaged by the readily distortable portion on the gland to. distort said readily distortable portion into close engagement with the sticking taper of the insulating core upon inward progression of said gland and core within the shell.

11. The herein described method of seating an insulating core having a sticking taper in a spark-plug shell provided with a complemental sticking taper, which consists in inserting the insulating core within a threaded gland, in threading the gland into the sparl -plug shell to rotate the gland against the complemental sticking taper in the spark-plug shell to spin the said gland on and around the sticking taper on the insulating core and between the same and the complemental sticking taper in the sparkplug shell,

12. The herein described method of seating an insulating core having a sticking taper within a spark-plug shell having a complemental sticking taper, which consists in providing a metal band around the sticking taper of the insulating core, and in progressing by rotation the insulatin core and metal band-inwardly of the spar -plug shell to dispose said metal hand against the complemental sticking taper of the sparkplug shell and between the same and the sticking taper of the insulating core. 5

13. The herein described method of seating an insulating core having a sticking taper within a spark-plu shell having a sticking taper, which conslsts in inserting a core-retaining gland having a tubular portion and the slightly tapered insulating core within the slightly tapered spark-plug shell, and in rotating the gland against the sticking taper of the spark-plug shell to spin the tubular portion of the gland between the insulating core and the ark-plu shell.

14. The herein describedmet 0d of seating an insulating core having a sticking taper within a spark-plug shell having a sticking taper, which consists in relatively rotating a threaded core retaining gland within and with relationto' a spark-plug shell to. relatively progress. the core-retaining gland against the complemental sticking taper of the spark-plug shell to spin the core retaining gland between the complemental tapers of the insulating core and the spark- -plug shell. 7

15. The herein described method of seating an insulating core having a sticking taper Within a spark-plug shell having a complementally sticking taper,rwhich consists in relatively progressing a, threaded core-retaining gland inwardly of a spark- .plug shell and against the sticking taper therein to distort the threaded coreretain- :inggland and spin the samebetween the complemental tapers of the insulating core and the spark-plug shell. 7 V

16. The herein described. method of retaining an insulating core having a sticking I taper Within a spark-plug gland, which consists in relatively progresslng a threaded core-retaining gland inwardly of a shell having a sticking taper complemental to the taper in the shell and on and around the sticking taper of the insulating core.

In testimony whereof, I affix my signature I 'inpresence of two witnesses.

7 CHARLES HUGH DUFFY.

Witnesses: p Y

HARRY A. HEGARTY, E. M. DIXON.

Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

' Washington, D. 0; 

